US5223925A

Movatterモバイル変換

Info

Publication number: US5223925A
Application number: US07/783,348
Authority: US
Inventors: Tomohiko Hattori
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-10-28
Filing date: 1991-10-28
Publication date: 1993-06-29
Anticipated expiration: 2011-10-28

Abstract

An autostereoscopic system has a taking section for taking an image of a predetermined reference plane and outputting an image signal composed of a plurality of parallax images based on the taken image of the predetermined reference plane, and a playback section for reproducing a 3-D image based on the image signal output by the taking section. The taking section is composed of TV cameras, each having a convex lens and an image pickup screen, which are arranged in the horizontal direction, and the playback section is composed of image output screens arranged in the horizontal direction for outputting inverted parallax images of those at the image pickup screen, a large Fresnel convex lens disposed in front of the image output screens, and convex lenses, each being disposed between each of the image output screens and the large Fresnel convex lens, for projecting the inverted parallax images on or along the effective lens plane of the large Fresnel convex lens.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an autostereoscopic system, and more particularly to an autostereoscopic system which permits the observation of a three-dimensional image by several persons simultaneously and is suited to mass production.

2. Description of the Prior Art

Conventional autostereoscopic systems include an Anaglyph system using special polarized glasses or shutter glasses; glasses-free systems such as a parallax stereogram, a lenticular system, a large concave mirror system and a large convex lens system; multiplex systems such as a parallax stereogram, integral system and a lenticular system using a lenticular sheet: spatial modulation such as a varifocal mirror system, a rotary cylinder system, a screen laminating system, a half-mirror synthesizing system and a screen vibrating system: holography such a laser playback holography and white light hologram.

However, these systems are not practical for general domestic and business purpose, although they can be used in certain special situations.

In broadcasting media, Anaglyph system using red and blue glasses, and density difference system using Pulfrich effect have been tried. However, these systems have drawbacks that special glasses are required and a look around capability is not obtained. Accordingly, these systems are difficult to be put to practical use.

The above-described conventional systems have features as shown in Table 1.

As is apparent from Table 1, systems other than the glasses, systems also have drawbacks such as that the reproduced image cannot be observed simultaneously by plural persons, that the systems are not suited to mass production, high resolution cannot be obtained, or they do not have a look around capability. Therefore, autostereoscopic system which can be practically used for both domestic use and business use has not been realized as yet.

In Table 1, ⊚ means "possible with especially good result", ◯ means "possible", Δ means "sometimes possible" and × means "impossible".

                                  TABLE 1                                 __________________________________________________________________________                       Watching               Look                                          Playback                                                                       by                     around                                        of land-                                                                       plural                                                                         Color-                                                                        Anima-                                                                        Mass pro-                                                                       Reso-                                                                         capa-                       Kind of 3D images                                                                    Glasses                                                                          scape                                                                          persons                                                                        ing tion                                                                          duction                                                                         lution                                                                        bility                      __________________________________________________________________________Binocular 3D images                                                       Anagliph method                                                                      Necessary                                                                        ◯                                                                  ◯                                                                  X   ◯                                                                 ◯                                                                   ◯                                                                 X                           Polarization method                                                                  Necessary                                                                        ◯                                                                  ◯                                                                  ◯                                                                 ◯                                                                 ◯                                                                   ◯                                                                 X                           Time sharing method                                                                  Necessary                                                                        ◯                                                                  Δ˜◯                                                    ◯                                                                 ◯                                                                 ◯                                                                   ◯                                                                 X                           No glasses method                                                                    Unnecessary                                                                      ◯                                                                  X    ◯                                                                 ◯                                                                 ◯                                                                   ◯                                                                 X                           Real 3D images                                                            Multiplex method                                                                     Unnecessary                                                                      ◯                                                                  X˜Δ                                                                ◯                                                                 ◯                                                                 Δ                                                                         X   Δ                     (Integral method)                                                         Spatial modulation                                                                   Unnecessary                                                                      X    Δ                                                                        ◯                                                                 Δ                                                                       Δ                                                                         Δ                                                                       ◯               Holography Unnecessary                                                                      X    ◯                                                                  X˜◯                                                         X˜◯                                                         X     Δ                                                                       ⊚            __________________________________________________________________________

SUMMARY OF THE INVENTION

It an object of the present invention is to provide an autostereoscopic system which enables reproduced images with high resolution, simultaneous observation of a reproduced image by plural persons without using special glasses while imparting a look around capability prevention of an increase of the frequency band width of image signals, and which is suited to mass production.

In order to achieve the above object, the present inventor has contemplated various systems in developing the present invention. One system among them is shown in FIGS. 7 and 8.

As shown in FIG. 7, in the taking sect ion, fourTV cameras 1 are arranged in parallel with each other in the horizontal direction so that the image pickup screens S (FIG. 8); ofvidiocons 12 of theTV cameras 1 are located on the same vertical plane. Each TV camera i is provided with alens 11 of which an optical axis to perpendicularly intersects to each image pickup screen S.

The image pickup screen S are arranged so that eachTV camera 1 takes an image of apredetermined reference plane 2.

Based on four image signals from the fourTV cameras 1, four electron guns and polarized coils within four cathode ray tubes (CRTs 5 scan electron fanbeams only in the vertical direction using vertical focusing according to the TV image horizontal scanning signals from theTV cameras 1. The electron fanbeams are separated into four areas of the phosphor plane as animage output screen 6 ofCRTs 5, and synchronized with vertical image scanning at the image pick-up screens S thevidicons 12 of the fourTV cameras 1.

A large horizontally focusingcylindrical lens 20 is disposed in front of theimage output screens 6. Avertical slit 21 is provided movably in the horizontal direction on or along the effective lens plane of the large horizontally focusingcylindrical lens 20.

A large vertically focusingcylindrical lens 22 is further disposed between theimage output screens 6 and the horizontally focusingcylindrical lens 20.Reference numerals 3, 4 designate coaxial cables for TV images and a vertical scanning signal, respectively.

With the system having the above-described constitution, by horizontally scanning thevertical slit 21 in the direction opposite to that of the horizontal image scanning at the image pickup screens S of theTV cameras 1 in synchronization therewith, n parallax images on thepredetermined reference plane 2 are reproduced on the plane of thevertical slit 21.

By disposing the vertically focusingcylindrical lens 22 between theimage output screens 6 and the horizontally focusingcylindrical lens 20, the vertical component of the image also can be also projected on the plane of thevertical slit 21 without influencing the horizontal component of the image. This results in both the horizontal component and vertical component of the reproduced three-dimensional (3-D) image appearing on the plane of thevertical slit 21 without any distortion.

Hereinafter, the above-described system ill be explained with reference to FIG. 8 which is a plan view of optical paths in t he system.

Both the distance between thereference plane 2 and theconvex lens 11 of theTV cameras 1 and the distance between theimage output screens 6 and the plane of thevertical slit 21 are two times the focal length (f) of the horizontally focusingcylindrical lens 20.

The focal length of the vertically focusingcylindrical lens 22 disposed between theimage pickup screens 6 and the horizontally focusingcylindrical lens 20 is f/2.

The horizontally movable range of thevertical slit 21 is identical to the horizontal length (G) of thereference plane 2. In theimage output screens 6, the distance between the center of thearea 6₁ and the center of thearea 6_n is identical to G.

The ray which passes the reference point a and is incident on theconvex lens 11 of theTV camera 1₁ reflects at the point a₁ on the image pickup screen S. Theimage output screen 6₁ of the playback section emits luminance corresponding to that of the point a₁.

When the horizontally scanning position on the image pickup screen S is a₁, thevertical slit 21 is positioned at the point a' and emits a fanbeam A1.

With regard to the rays which are incident on theother TV cameras 1₂ to 1_n, fanbeams A2 to An are emitted from the vertical slit positioned at the point a' similarly to the case of the fanbeam A1.

As a result, n slit-like different parallax images are produced.

With regard to the point b on thereference plane 2, fanbeams B1 to Bn are emitted from the point b' on the plane of thevertical slit 21 to produce n different parallax images similarly to the case of the rays to the point a.

Accordingly, due to the movement of thevertical slit 21 by the length G, a 3-D image composed of n parallax images can be viewed. The most suitable observation position of the 3-D image is distant from the plane of thevertical slit 21 by 2f.

When n is 3 or more, the look around capability is imparted.

As a result of many studies, the present inventor has succeeded in the development of the autostereoscopic system which is produced more inexpensively and is more practical, as compared with the above-described system provided with a vertical slit.

The system of the present invention has a taking section for taking an image of a predetermined reference plane with its taking range coincided with the predetermined reference plane, and outputting an image signal composed of a plurality of parallax images based on the taken image of the predetermined reference plane, and a playback section composed of an image output screen having a plurality of image output areas arranged in parallel with each other in the horizontal direction for outputting a plurality of inverted parallax images of those of said image signal output by the taking section, a large format lens disposed in front of the image output areas of the image output screen, and a plurality of image projecting members arranged in parallel with each other in the horizontal direction with substantially no space therebetween. The plurality of image projecting members are disposed between the image output screen and the large format lens for projecting the inverted parallax images on or along the effective lens plane of the large format lens in the range equivalent to the reference plane.

The autostereoscopic system of the present invention has advantages similar to those of the system provided with a vertical slit. Furthermore, the system of the present invention has another advantage that it is unnecessary to provide both the vertical slit and the vertically focusing cylindrical lens because the image projecting members disposed in front of the image output screen project rays which direct to the large format lens in various directions.

Moreover, it is not necessarily required to synchronize the n image scanning with the image signal.

As is apparent from the foregoing, the system of the present invention solves all the drawbacks of the conventional systems. The system of the present invention enables the playback of 3-D images with high resolution, simultaneous observation of the reproduced 3-D image by plural persons without using special glasses while exhibiting a look around capability, and is suited to mass production.

BRIEF DESCRIPTION OF THE DRAWING

Other objects, features and characteristics of the present invention will become apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification.

FIG. 1 is an overall perspective view of a first embodiment of an autostereoscopic system in accordance with the present invention;

FIG. 2 is a plan view of optical paths in the first embodiment;

FIG. 3 is an overall perspective view of a second embodiment of an autostereoscopic system in accordance with the present invention;

FIG. 4 is an overall perspective view of a third embodiment of an autostereoscopic system in accordance with the present invention:

FIG. 5 is an overall perspective view of a fourth embodiment of an autostereoscopic system in accordance with the present invention;

FIG. 6 is an overall perspective view of a fifth embodiment of an autostereoscopic system in accordance with the present invention;

FIG. 7 is an overall perspective view of an autostereoscopic system contemplated by the inventor during his development of the system of the present invention; and

FIG. 8 is a plan view of optical paths in the system of FIG. 7.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS

Regarding FIGS. 1 and 2 which illustrate a first embodiment of the present invention, the number of the parallax images is set to an arbitrary number, and the same number of TV cameras are prepared. In the first embodiment, the number of the parallax images is set to four and four TV cameras are arranged in parallel with each other in the horizontal direction.

EachTV camera 1 has aconvex lens 11 composed of a relatively large image circular lens having a focal length identical to that of anotherlens 11. Previously, theconvex lenses 11 are moved in the horizontal direction so as to take an image of apredetermined reference plane 2 and are held in place. Thus, the taking section of the autostereoscopic system is so composed.

FourTV cameras 1 are connected to respective fourCRTs 5, each having a flatimage output screen 6, by ay of fourcoaxial cables 3 in the order opposite to the order of theTV cameras 1.

Convex lenses 7 as t he image projecting members are disposed in front of the respectiveimage output screens 6 of theCRTs 5. A large Fresnelconvex lens 8 as the large format lens is disposed in front of theconvex lenses 7.

Eachlens 7 is 6.5 cm in diameter and 6.3 cm in focal length. The large Fresnelconvex lens 8 is 20 cm in focal length, 24.4 cm in length and 32.5 cm in width.

The distance between theimage output screens 6 and the convex lenses is 5 cm, the distance between theconvex lenses 7 and the large Fresnelconvex lens 8 is 40 cm which is two times the focal length of the large Fresnelconvex lens 8. The distance between the large Fresnelconvex lens 8 and the most suitable observation position is also 40 cm.

Thereference plane 2 is 24.4 cm in length and 32.5 cm width. The distance between thereference plane 2 and the effective lens plane of the fourlenses 11 of theTV cameras 1 is 40 cm. Thereference numeral 12 designates a vidicon of eachTV camera 1.

With the system of t he first embodiment having the above-described constitution, the geometric configuration of the optics which is shown in FIG. 2 is equivalent to that shown in FIG. 8.

The images of thereference plane 2 taken by theTV cameras 1 in the taking section are output at theimage output screens 6 of theCRTs 5 in the playback section as inverted parallax images of the parallax images at the image pickup screens S of the TV cameras.

Theimage output screens 6 respectively project rays to the effective lens plane of the large Fresnelconvex lens 8 by way of theconvex lenses 7.

The projected images can be viewed at the position distant from the effective lens plane of the large Fresnelconvex lens 8 by the distance two times the focal length (f) of the large Fresnelconvex lens 8.

With regard to the ray passing the point a on thereference plane 2, for example, theimage output screens 6₁ to 6_n output rays to the point a' on the effective lens plane of the large Fresnelconvex lens 8 after passing theconvex lenses 7. Then, fanbeams A1 to An are emitted from the point a' of the large Fresnelconvex lens 8 with the result that n different parallax images are produced.

With regard to the ray passing the point b on thereference plane 2, the point b' on the effective lens plane of the large Fresnelconvex lens 8 emits fanbeams B1 to Bn with the result that n different parallax images are produced.

As a result, a 3-D image composed of n parallax images is produced based on the rays passing all points on thereference plane 2.

The first embodiment satisfies the following image forming equation:

1/d+1/D=1/f

where f is the focal length of the large Fresnelconvex lens 8, d is the distance between the effective lens plane of eachlens 7 and that of the large Fresnelconvex lens 8, and D is the distance between the effective lens plane of the large Fresnelconvex lens 8 and the most suitable 3-D image observation position.

With the first embodiment, both the horizontal and vertical resolution of the 3-D image are determined only by the vertical resolution of theimage output screens 6 of theCRTs 5. Therefore, the resolution of the system of the first embodiment is higher, as compared with the conventional system using a horizontally focusing lenticular plate so that the system of the first embodiment can be applied to the high resolution system such as HDTV.

Furthermore, in the system of the present embodiment, n channels of TV lines are sufficient for playing back the 3-D image composed of n parallax images. Accordingly, the frequency band width is not overly increased.

Moreover, with the present embodiment, a look around capability is obtained if the number of the parallax images is 3 or more, and a 3-D image can be simultaneously viewed by plural observers without lasses or other special instrument. Therefore, the system of the first embodiment can be put into practical application, and the overall system is suited to mass production.

In addition, the 3-D playback of landscape pictures or animation pictures, and coloring of the 3-D image are also possible. Accordingly, the system of the present embodiment is free from the drawbacks of the conventional holography system.

FIG. 3 illustrates a second embodiment of the present invention.

In the second embodiment, eachconvex lens 7 which is disposed in front of each of theimage output screens 6 of theCRTs 5 has an elongated configuration in the vertical direction. The remainder of the constitution of the system of the second embodiment is identical to that of the first embodiment.

With the second embodiment, similar operational effect to that of the first embodiment can be achieved.

Moreover, with the second embodiment, the vertical observation area can be extended because such area increases with the increase in the vertical length of theconvex lenses 7.

FIG. 4 illustrates a third embodiment of the present invention.

In the third embodiment, a vertically focusinglenticular sheet 9 is disposed near the large Fresnelconvex lens 8 and faces theconvex lenses 7. The vertically focusinglenticular sheet 9 is 0.5 mm in pitch, 1.25 mm in focal length, 24.4 cm in length and 32.5 cm in width.

The remainder of the constitution of the system of the third embodiment is identical to that of the first embodiment.

The vertically focusinglenticular sheet 9 diffuses rays only in the vertical direction. Therefore, the third embodiment also achieves the same operational effect as that of the second embodiment.

FIG. 5 illustrates a fourth embodiment of an autostereoscopic system in accordance with the present invention.

In the fourth embodiment, a plurality ofCRTs 5 are arranged in parallel with each other in the vertical direction in addition to the horizontal direction so that theimage output screens 6 of theseCRTs 5 are located on the same plane. OneTV camera 1 outputs an image signal to the vertically arrangedCRTs 5 which are located at the horizontally inverted position of that of theTV camera 1.

The remainder of the constitution of the system of the fourth embodiment is identical to that of the first embodiment. The system of the fourth embodiment can achieve similar operational effect to that of the second embodiment.

FIG. 6 illustrates a fifth embodiment of an autostereoscopic display system in accordance with the present invention.

In the fifth embodiment, a plurality of TV cameras and a plurality of CRTs are arranged in parallel with each other in the vertical direction in addition to the horizontal direction so that both thelenses 11 of theTV cameras 1 and theimage output screens 6 of theCRTs 5 are located on the same plane, respectively. OneTV camera 1 outputs an image signal to oneCRT 5 which is located at the horizontally and vertically inverted position of that to the oneTV camera 1.

The remainder of the constitution of the fifth embodiment is identical to that of the first embodiment.

The system of the fifth embodiment can achieve similar operational effect to that of the first embodiment. Furthermore, an image with both horizontal and vertical parallax can be obtained, thereby imparting depth to the vertical component as well as the horizontal component.

The present invention is not limited to the preceding embodiments. Various modifications are possible.

For example, in place of one large Fresnel convex lens, at least one other large format lens such as a large convex lens, a large concave mirror, a large Fresnel concave mirror, a horizontally focusing Fresnel cylindrical lens and a holographic lens may be used.

When the horizontally focusing Fresnel cylindrical lens is used, a lenticular sheet is used in combination therewith. When a plurality of the above described lenses are used, they are arranged with their optical axes aligned in the horizontal direction.

With regard to the image projecting members in the playback section, in place of the convex lenses, other members such as concave mirrors, Fresnel convex lenses and holographic lenses may used. Or, a plurality of the above-described lenses may be used with their optical axes aligned in the horizontal direction.

With regard to the image output screens, in place of a plurality of output screens, an integral output screen may be used.

With regard to CRT, in place of it, plasma display, light emitting diode or liquid crystal display may be used.

With regard to the taking section, in place of the TV cameras, computer generated images may be used.

Furthermore, the transmission system from the taking section to the playback section may be arbitrarily modified within the scope of the present invention.

Moreover, various images other than three dimensional image can be obtained by arbitrarily selecting the number of parallax images. For example, by alternately displaying the image output screens composed of 1 to n parallax images as a left eye image and a right eye image, stereo images can be observed in the horizontally extending wide range. Or by outputting the same two-dimensional images in every image output screen, the system of the present invention can serve as the two dimensional image display system.